The continued objective is to provide biomechanical information on the knee joint that can be used to improve the treatment of arthritis of the knee. Previous work has indicated that biomechanical function can be influenced by the design of a total knee replacement. In addition, recent results suggest a relationship between dynamic functional loading and clinical results in patients in patients with high tibial osteotomies. The goal is to examine the interrelationships between dynamic functional loading and clinical results with total knee replacement and high tibial ostetomy. The general hypothesis is that dynamic functional loading is related to post-operative clinical results. Specific goals relating to this hypothesis are the following: 1) to identify if time-related functional biomechanical changes can be correlated with clinical and radiographic changes at five to seven years following surgery, 2) to identify if correlations exist between pre-operative functional biomechanics and post-operative functional biomechanics following total knee replacement, 3) to identify if functional loading abnormalities can be associated with the use of cementless fixation of total knee replacement, 4) to validate our initial findings that pre-operative knee joint loading is strongly predictive of clinical results in patients with high tibial osteotomies. Biomechanical functional testing will be conducted for level walking, stairclimbing and chair rising to determine extrinsic joint movement and loading patterns. This information will be analyzed independently as well as provide input to mathematical and in vitro models to analyze intrinsic joint loads. Biomechanical data will be correlated with quantitative clinical and radiographic evaluations. Ultimately, this information will be useful in identifying functional loading characteristics that correlate with clinical results and radiographic changes. Adaptive mechanisms will be identified and their implication to joint alignment, component fixation and clinical outcome will be evaluted.